Ilaria Ramelli is a superb scholar, and if you are at all inclined to look into the subject of Christian Universalism, she would be among the first I would recommend consulting. Her most recent volume, A Larger Hope?, Volume 1: Universal Salvation from Christian Beginnings to Julian of Norwich is a highly accessable summary of her academic tome The Christian Doctrine of Apokatastasis: A Critical Assessment from the New Testament to Eriugena. Toward the end of A Larger Hope? Volume 1, Ramelli provided a succinct summary of the architecture of the Christian doctrine of universalism:
This [Christian Universalism] is not a doctrine that arises from moral relaxation – as it was depicted during the Origenistic controversy- but the expectation of the total victory of God over evil, which is grounded in the inhumanation, death and resurrection of Christ, his work as Logos-teacher and physician, and in God’s “goodness.” This goodness is not simply God’s kindness or mercy, but it is God’s being the absolute Good – with the relevant corollary of the ontological non-substantiality of evil, which is doomed to disappearing, Evil will not exist any longer when in the end no one will choose it any more, and once all have been illuminated, purified, and healed. Purification, according to the supporters of universal salvation, will be commensurate to each one’s sins and therefore finite. Death itself in any case puts a providential limit to everyone’s sins – as Origen, Methodius, Gregory of Nyssa, and others later reflected, up to our day – so that their purification will not have to go on forever. As Gregory of Nyssa as clear, right until the end of his life, in his homilies on the Song of Songs, that the divine will shall be fulfilled (“until the One who wants all humans to be saved has reached his aim”). The Christian hope, which is given voice by St. Paul in 1 Corinthians 15:24-28, is that in the end, when all have been purified and illuminated by Christ-Logos and all evil has been eliminated, all those who were enemies will submit in what Origen and many theologians over the centuries regarded as salvific submission, whereas “the last enemy,” death, which is no creature of God, will be destroyed. Then St. Paul’s prophecy [will] come true that “God will be all in all” (1 Cor 15:28).